1. Field of the Invention
The present invention relates to a transmission mechanism which transmits an operational force of a raising operation portion to a raising stand to raise the raising stand that raises an insert object, a raising device having the transmission mechanism, and an insertion apparatus having the raising device.
2. Description of the Related Art
For example, a treatment instrument and a guide member which guides the treatment instrument to a subject function as an insert object to be inserted into an insertion portion of an endoscope.
In the endoscope, the insert object is mounted on a raising stand, and protrudes toward the lateral side of the insertion portion from a distal opening portion. In this state, the raising stand is raised by the operation of a raising operation portion, whereby the insert object comes closer to the subject, and becomes able to treat the subject. The thickness and hardness of the insert object vary according to purposes.
When a thin insert object or a soft insert object is used, the raising stand can raise to a maximum angle with small force even if the insert object is mounted on the raising stand. However, when a thick insert object or a hard insert object is used, the raising stand only raises halfway due to the thickness or hardness if the insert object is mounted on the raising stand. Much force is needed for the raising stand to raise to the maximum. In this case, members constituting a transmission mechanism such as a wire member to raise the raising stand are loaded by the great force.
For example, in Jpn. Pat. Appln. KOKAI Publication No. 2003-245248, an adjustment unit of a transmission mechanism has an expansion and contraction member which is coupled to a slider mechanism and a proximal end portion of an operation wire. The expansion and contraction member is a coil spring which expands and contracts to adjust the distance between the slider mechanism and the proximal end portion of the operation wire. The expansion and contraction member prevents breakage of the transmission mechanism by the adjustment of the distance. The expansion and contraction member also adjusts the raise angle of the raising stand by the adjustment of the distance.